No if you want to oc your cpu you should read forums on overclocking sandybridges like we all had to do. Only you can set the correct voltage and get a higher download, it's not that hard overclock by starting at 4.5 which is a 45 multiplier and raise the vcore to one encriment until you run stabe in prime 95 for a couple of hours. Overclocking is easy you just need to start reading.
The EZ Auto overclocking feature Asus has works well, but like you said, only to 3.5GHz. The reason for that is simple - it doesn't play with your core multiplier, it simply increases the FSB speed, making for decent speeds but begin limited by your RAM, motherboard and CPU FSB speed support. The whole wonder about the 2500K CPU is that it allows for core multiplier modification, which is what you really want to play with. Do it manually, it's much, much more satisfactory!
You're right, I started at 40 cuz its my only pc and no more budged for parts until later. Corsair PSU died after a couple of weeks, and was wondering if it was Asus EZ Auto. It probably was a just a bad PSU... Im so lucky
I'm going to play it safe at 45 for now. It is satisfactory